1. Field of the Invention
The present invention relates to a radiation-sensitive resin composition.
2. Discussion of the Background
A chemically-amplified radiation-sensitive resin composition generates an acid when exposed to deep ultraviolet rays (e.g., KrF excimer laser or ArF excimer laser) or electron beams. A difference in solubility rate in a developer occurs between the exposed area and the unexposed area due to chemical reactions catalyzed by the generated acid so that a resist pattern is formed on a substrate.
A compound that generates a perfluoroalkanesulfonic acid (e.g., trifluoromethanesulfonic acid or nonafluorobutanesulfonic acid) has been used as the acid generator. However, such a compound may remain undecomposed in the environment, or may be accumulated in a human body.
A chemically-amplified resist has been required to have high resolution and form a smooth pattern in order to more accurately control the line width.
Various acid generators have been proposed aimed at adjusting the acidity or changing the diffusion length or the distribution of the acid generated in the resist film (see Japanese Patent Application Publication (KOKAI) No. 2004-002252, Japanese Patent Application Publication (KOKAI) No. 2005-266766, United States Patent Application Publication No. 2006/0276670, Japanese Patent Application Publication (KOKAI) No. 2007-145803, and Japanese Patent Application Publication (KOKAI) No. 2008-094835, for example). A method that utilizes an acid other than sulfonic acid for the chemically-amplified resist as an acid generator has also been proposed (see U.S. Pat. No. 5,554,664 and Japanese Patent No. 3937466). However, the desired performance has not been achieved by such a method.
The above composition exhibits well-balanced resist performance by utilizing acid generators having various structures. However, since the line width of the resist pattern has been reduced to 90 nm or less, various other properties have been required for resist compositions. Specifically, development of a material that satisfies various properties (e.g., line width roughness (LWR), mask error enhancement factor (MEEF), iso-dense bias, and storage stability (changes in foreign matter content and sensitivity with time)) has been desired.